Minneapolis and St. Paul, like much of the USA, are at risk from tornadoes. Southern Minnesota, including the Twin Cities metro area, is regarded to be in Tornado Alley, and the Twin Cities are among the top 15 US cities most likely to be struck by a tornado.

Tornadoes can be devastating, but you can significantly reduce the risk to you and loved ones by being prepared, and knowing what to do if a tornado does hit. Most deaths and injuries happen to people taken by surprise. Many more happen to people who hear tornado warnings, but disregard them.

When Are Tornadoes Likely In Minneapolis and St. Paul?

The peak tornado season for Minneapolis and St. Paul is May, June, and July. However, tornadoes can and do strike outside these months. In the past, tornadoes have struck Minnesota in every month from March until November.

How Will I Know If a Tornado is Approaching?

Outdoor emergency sirens, often referred to as tornado sirens, are sounded when a tornado has formed. Sirens are sounded when the National Weather Service issues a tornado warning. They are also sounded if a tornado is sighted by a trained spotter, a firefighter or police officer, or if a sighting by a member of the public is confirmed.

Sirens are located across the Twin Cities.

But don't assume that because there is no siren, there is no danger.

While there are outdoor emergency sirens across the Twin Cities, they may not sound for every tornado. When a devastating tornado hit the unfortunately-named Siren, Wisconsin, in 2001, no emergency siren sounded. The siren was broken, and even if it had been working, the power was out and the siren, like many in Wisconsin and Minnesota, had no battery backup.

Tornadoes can form very fast, in some cases too fast for the sirens to be sounded in time.

Here in the Twin Cities, the Hennepin County sirens didn't sound in the 2006 Rogers Tornado, which killed a ten-year-old girl. The National Weather Service said that a convoluted and fast-moving weather pattern meant that there was no time to sound the sirens before the tornado hit the town of Rogers and northern Hennepin County.

If the emergency sirens are sounded, they are not audible everywhere.

The outdoor emergency sirens are designed to be heard outdoors, and people in buildings may not hear them. I can only hear the sirens being tested faintly from my home, and I can't hear sirens at all in a store or bigger building.

So the sirens may not work, they may not sound in time, and if they do, you might not hear them. So it's important to watch the weather too. Most residents of the Twin Cities are in the habit of frequently checking the weather on the radio, television, newspaper or internet, and it's a wise habit to adopt.

Be alert to what's happening outside, especially if the weather is turning stormy. Listen for tornado watches and warnings on local television or radio.

What Weather Signs Indicate a Possible Tornado?

These are some visual signs that should be taken as a warning of an imminent tornado,

A green or green-black sky

A funnel-shaped cloud

A low-lying, black cloud

Swirling dust or debris, debris falling or being pulled upwards

Hail, thunder or lightning

Strange cloud behavior, such as clouds moving very fast, swirling or converging

A sudden drop in temperature

A sudden calm after wind, when the air becomes very still

Tornado witnesses often report that they "felt" it coming before the tornado formed. Tornadoes are associated with low air pressure, which the body can sense. If your body is telling you there's danger, you would be wise to listen.

Although synonymous with tornadoes for most people, a funnel may or may not be visible. Not all tornadoes have a visible funnel. Funnels may be surrounded and hidden by dust or rain.

Tornadoes can, but do not always, make noise. The sounds made are described as whooshing roars, or something similar to a jet engine, freight train, or rushing water. Funnels can also make whining or buzzing sounds. The sound does not travel far, so if you can hear a tornado, it is very close. Seek shelter immediately.

Tornado Watches and Tornado Warnings

The National Weather Service issues tornado watches and tornado warnings. What's the difference?

Tornado Watch: A watch means conditions are favorable for the formation of tornadoes, but no actual tornado has been seen by spotters or can be seen on doppler radar. Listen to local weather reports, pay attention to the weather, and be prepared to take shelter if necessary. Alert friends, family, and neighbors of the warning.

Tornado Warning: A warning means a tornado has been spotted, or doppler radar shows a tornado is forming or has formed. If a tornado warning is issued for your area, seek shelter immediately. A tornado warning means that a tornado is very close and may strike within minutes.

What Should You Do in the Event of a Tornado?

If the emergency sirens sound, or if you hear a tornado warning, or see a tornado or signs of a tornado in the sky, take shelter immediately.

The best shelter depends on where you are.

The safest place to be is in a basement or a designated storm shelter. Many large public buildings have special severe weather shelters.

If there is no basement, a small interior room, bathroom, or closet on the first floor is the next best place.

Under a stairwell in the basement or on the first floor is also a sturdy part of a structure and may be the best refuge for apartment dwellers.

Get under a sturdy piece of furniture if possible. Cover yourself with blankets or pillows to protect yourself from falling debris. Try to avoid locations where heavy furniture is immediately above you on higher floors.

Always stay away from windows.

If you are outside, seek a sturdy shelter. If there is no substantial shelter nearby, lie in a ditch or low spot, and cover your head with your hands.

If you are in a car, don't try to outrun the tornado. Tornadoes can travel faster than your car. If you are hit, the car will be tossed in the air and you will likely be killed. Get out of the car and seek shelter. Many people are killed every year trying to drive away from tornadoes. If you must drive away, quickly assess the direction the tornado is moving in, and drive at right angles to it, out of its path.

Many tornado casualties are people in mobile homes. If you are in a mobile home, evacuate it for more substantial shelter if possible. Some mobile home parks have a tornado shelter. If there's no shelter close by, you are still safer outside. Get away from the homes, to avoid flying debris, and into a low-lying area or ditch. Lie flat and cover your head with your hands.

Preparing for a Tornado

Tornadoes are inevitable. The chances of one hitting you are very small, but there is still a real risk. Everyone should be prepared and know what to do in the event of a tornado.

The people with the best chance of survival in a tornado are those who are prepared, those who hear the warnings, and then take action.

Determine a shelter in your home, based on the criteria above. Know the locations of severe weather shelters at work, and in buildings you visit frequently. Discuss what to do in a tornado with your family.

Get a battery-powered radio, and take it with you to your shelter in a tornado.

Have a disaster supply kit with essential supplies in your shelter, or readily reachable to be taken to the shelter.

Minnesota's schools are required by law to have an emergency plan for children and teachers to follow. If your child's school does not, ask them to implement one.

Minnesota school bus drivers are instructed what to do if they see a tornado, or receive a tornado warning on their radio.

Major employers and large organizations usually have a tornado drill to follow. If your place of work, church, or other place where people gather does not have a plan, then start one.

Tornado Spotters: SKYWARN

Tornadoes can often be seen on the ground by an observer before the National Weather Center's radar can detect them. SKYWARN spotters are trained volunteers who look out for severe weather, and alert the National Weather Service, who can then issue a severe weather warning.

Since the SKYWARN program began in the 1970s, the volunteers have helped the NWS issue more timely warnings of tornadoes, and other severe weather, and have saved many lives.

Tornado strength is measured in various ways, but the most commonly used in the US is the Fujita Scale, which uses the wind speed and damage caused to give a tornado a rating from F0 - gale force winds, light damage - to F5 - incredibly devastating, violent tornadoes.

In 2007 the Fujita Scale was replaced by the Enhanced Fujita scale. The new scale is very similar to the original, it also grades tornadoes from EF0 to EF5, but slightly re-categorizes tornadoes reflecting the latest knowledge of damage caused by different wind speeds.

Historical Tornadoes in the Twin Cities Area

The Minneapolis Tornado, August 19, 2009: Several tornadoes touched down in the Twin Cities early one Wednesday afternoon, the largest of which damaged a church, the Electric Fetus record store, the Minneapolis Convention Center, and several other buildings just south of downtown Minneapolis.

The Hugo Tornado, May 25, 2008: At around 5 p.m., a tornado ranked EF-3 touched down in Lino Lakes, a northeast suburb of St. Paul, and cut through the town of Hugo. The tornado destroyed 50 houses, killed a two-year-old boy and seriously injured eight more people in Hugo. The tornado hit on Memorial Day weekend, possibly saving many other people who were out of town when the tornado hit.

The Rogers Tornado, September 16, 2006: This tornado that hit the Twin Cities metro area struck northern Hennepin County in the late evening. The F2 tornado struck at around 10 p.m. and destroyed over 300 buildings and homes. One ten-year-old girl was killed when her home collapsed.

The Har Mar Tornado, Sunday June 14, 1981: The Har Mar Tornado, an F3 tornado, is also known as the Edina Tornado, after the place where it first touched down. After touching down at 3:49 p.m., the tornado moved northeast through Minneapolis and Roseville, leaving 15 miles of devastation behind it. The worst damage was in the Har Mar mall area. One man was killed in the tornado itself, 83 were injured, and another man died in the cleanup effort.

The Twin Cities Tornado Outbreak, May 6, 1965: It's sometimes claimed tornadoes can't, or don't, hit metropolitan areas. It's not true. A tornado outbreak of six tornadoes caused $51 million of damage and killed 14 people when they passed within miles of downtown Minneapolis and St. Paul. Four of the tornadoes were rated F4, the other two were F3 and F2.

The St. Paul and Minneapolis Tornado, August 21, 1904: Another tornado that hit the metro area, this time causing damage to both downtown Minneapolis and St. Paul. 14 people were killed, and the High Bridge in St. Paul suffered significant damage.

The Sauk Rapids Tornado, April 14, 1886: The deadliest tornado in Minnesota history ripped through Sauk Rapids, St. Cloud, and Rice, just north of the Twin Cities. The town of Sauk Rapids was almost entirely destroyed, and 72 people were killed. Witnesses said the Mississippi river was temporarily sucked dry as the tornado crossed it.

The Rochester Tornado, August 21, 1883: An estimated F5 tornado hit Rochester directly, killing at least 37 people, injuring hundreds and devastating the town. At the time, Rochester did not have a hospital to treat the injured, so Doctor William Mayo and his two sons, together with Sisters of St. Francis, had to treat the victims in a makeshift emergency room. After the tornado, the doctors and the Sisters joined forces to create what became the Mayo Clinic in Rochester.

The Fort Snelling Tornado, April 19, 1820: The earliest recorded tornado in Minnesota history was at Fort Snelling, the year after primitive weather recording equipment was installed at the fort. No deaths or injuries were recorded.